title: Photodecarboxylation of DX-9065a, a new factor Xa inhibitor, in aqueous solution.
abstract: The photodegradation reaction of (2S)-2-[4-[[(3S)-1-acetimidoyl-3-pyrrolidinyl]oxy]phenyl]-3- (7-amidino-2-naphthyl) propanoic acid hydrochloride pentahydrate (DX-9065a), a new factor Xa inhibitor, was investigated in aqueous solution at various pH values (1.1-8.0) at 25 degrees C. The photodegradation of DX-9065a followed apparent first-order kinetics under artificial sunlight in a fairly good manner. The photodegradation rates of DX-9065a in a neutral solution were higher than those in acidic solution. The log k-pH profile indicated that the photodegradation rate of DX-9065a was related to the dissociation of the carboxyl group and suggested that the main photo-labile species was the carboxylate form. Further kinetic study showed that the carboxylate form of DX-9065a underwent decarboxylation quantitatively to produce D41-1077, the photodecarboxylation product, on irradiation, while the carboxylic acid form of DX-9065a did not perform any photodecarboxylation. Moreover, the photodecarboxylation mechanism was discussed in relation to the kinetics and photodegradation pathway.
authors.affiliation: Drug Metabolism and Analytical Chemistry Research Laboratory, Daiichi Pharmaceutical Co., Ltd., Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kawai
authors.forename: K
authors.initials: K
authors.lastname: Matsubayashi
mesh_terms: D065427:Factor Xa Inhibitors; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D009281:Naphthalenes / Q000737:chemistry*; D010777:Photochemistry; D011422:Propionates / Q000737:chemistry*; D015842:Serine Proteinase Inhibitors / Q000737:chemistry*; D012996:Solutions; D013472:Sunlight; D014867:Water
chemical_list: C086910:(2S)-2-(4-(((3S)-1-acetimidoyl-3-pyrrolidinyl)oxy)phenyl)-3-(7-amidino-2-naphtyl)propanoic acid; D065427:Factor Xa Inhibitors; D009281:Naphthalenes; D011422:Propionates; D015842:Serine Proteinase Inhibitors; D012996:Solutions; D014867:Water